我正在学习如何在C#中使用COM接口,所以我为(I)DxDiagProvider
和IDxDiagContainer
COM对象编写了一个coclass和接口。
然而,虽然明显等效的代码在C ++中运行良好,但调用其中一个方法失败,在C#中使用COMException
(HRESULT为-1)。我可能搞砸了把它移植到C#的东西,但看不到错误。
原生代码(工作)
对象在原始C中定义如下,这也是我对它们的唯一信息(没有tlbimp或任何东西的库):
struct IDxDiagContainerVtbl;
struct IDxDiagContainer { IDxDiagContainerVtbl* lpVtbl; };
struct IDxDiagContainerVtbl
{
HRESULT(__stdcall* QueryInterface)(IDxDiagContainer* This, const IID* const riid, void** ppvObject);
ULONG(__stdcall* AddRef)(IDxDiagContainer* This);
ULONG(__stdcall* Release)(IDxDiagContainer* This);
HRESULT(__stdcall* EnumChildContainerNames)(IDxDiagContainer* This, DWORD dwIndex, LPWSTR pwszContainer, DWORD cchContainer);
HRESULT(__stdcall* EnumPropNames)(IDxDiagContainer* This, DWORD dwIndex, LPWSTR pwszPropName, DWORD cchPropName);
HRESULT(__stdcall* GetChildContainer)(IDxDiagContainer* This, LPCWSTR pwszContainer, IDxDiagContainer** ppInstance);
HRESULT(__stdcall* GetNumberOfChildContainers)(IDxDiagContainer* This, DWORD* pdwCount);
HRESULT(__stdcall* GetNumberOfProps)(IDxDiagContainer* This, DWORD* pdwCount);
HRESULT(__stdcall* GetProp)(IDxDiagContainer* This, LPCWSTR pwszPropName, VARIANT* pvarProp);
};
struct DXDIAG_INIT_PARAMS
{
DWORD dwSize;
DWORD dwDxDiagHeaderVersion;
BOOL bAllowWHQLChecks;
void* pReserved;
};
struct IDxDiagProviderVtbl;
struct IDxDiagProvider { IDxDiagProviderVtbl* lpVtbl; };
struct IDxDiagProviderVtbl
{
HRESULT(__stdcall* QueryInterface)(IDxDiagProvider* This, const IID* const riid, void** ppvObject);
ULONG(__stdcall* AddRef)(IDxDiagProvider* This);
ULONG(__stdcall* Release)(IDxDiagProvider* This);
HRESULT(__stdcall* Initialize)(IDxDiagProvider* This, DXDIAG_INIT_PARAMS* pParams);
HRESULT(__stdcall* GetRootContainer)(IDxDiagProvider* This, IDxDiagContainer** ppInstance);
};
在本机C ++中创建它并调用Initialize
就可以了:
int main()
{
GUID clsid;
GUID iid;
CLSIDFromString(L"{A65B8071-3BFE-4213-9A5B-491DA4461CA7}", &clsid);
CLSIDFromString(L"{9C6B4CB0-23F8-49CC-A3ED-45A55000A6D2}", &iid);
CoInitialize(NULL);
IDxDiagProvider* pDxDiagProvider;
HRESULT hr = CoCreateInstance(clsid, NULL, 1, iid, (LPVOID*)&pDxDiagProvider); // S_OK
DXDIAG_INIT_PARAMS params;
params.dwSize = sizeof(DXDIAG_INIT_PARAMS);
params.dwDxDiagHeaderVersion = 111;
params.bAllowWHQLChecks = 0;
params.pReserved = 0;
// Sorry for the C-like access, I don't have anything better than the structs above.
hr = pDxDiagProvider->lpVtbl->Initialize(pDxDiagProvider, ¶ms); // S_OK
}
托管代码(已损坏)
然后我继续将其移植到具有以下定义的STAThread
x86 .NET 4.6.1 C#控制台程序:
[ComImport]
[Guid("A65B8071-3BFE-4213-9A5B-491DA4461CA7")]
public class DxDiagProvider { }
[Guid("9C6B4CB0-23F8-49CC-A3ED-45A55000A6D2")]
public interface IDxDiagProvider
{
void Initialize(ref DXDIAG_INIT_PARAMS pParams);
void GetRootContainer(ref IDxDiagContainer ppInstance);
}
[StructLayout(LayoutKind.Sequential)]
public struct DXDIAG_INIT_PARAMS
{
public uint dwSize;
public uint dwDxDiagHeaderVersion;
public bool bAllowWHQLChecks;
public IntPtr pReserved;
};
[Guid("7D0F462F-4064-4862-BC7F-933E5058C10F")]
public interface IDxDiagContainer
{
void EnumChildContainerNames(uint dwIndex, string pwszContainer, uint cchContainer);
void EnumPropNames(uint dwIndex, string pwszPropName, uint cchPropName);
void GetChildContainer(string pwszContainer, ref IDxDiagContainer ppInstance);
void GetNumberOfChildContainers(ref uint pdwCount);
void GetNumberOfProps(ref uint pdwCount);
void GetProp(string pwszPropName, ref IntPtr pvarProp);
}
现在,在创建类和转换界面时,对Initialize
的调用打破了COMException: Exception from HRESULT: 0xFFFFFFFF
:
[STAThread]
static void Main(string[] args)
{
// Working fine.
DxDiagProvider dxDiagProviderClass = new DxDiagProvider();
IDxDiagProvider dxDiagProvider = (IDxDiagProvider)dxDiagProviderClass;
DXDIAG_INIT_PARAMS initParams = new DXDIAG_INIT_PARAMS
{
dwSize = (uint)Marshal.SizeOf<DXDIAG_INIT_PARAMS>(),
dwDxDiagHeaderVersion = 111
};
dxDiagProvider.Initialize(ref initParams); // causes COMException
}
我不确定我做错了什么。到目前为止,我已经测试并检查了以下内容:
DXDIAG_INIT_PARAMS
结构具有正确的大小,对齐,布局IUnknown
方法DispIdAttribute
添加到接口方法中,即使我认为仅在托管COM对象而不使用它们时才有意义。ref
,因为参数是指针。我真的希望这与在托管应用程序中使用时COM对象无法正常工作无关(这肯定会使这个问题过于宽泛)。所以我想确保我的方法和我的定义至少是正确的。还有什么必须做的,而且我不在了吗?
我发现了我所缺少的东西,可以解决它:
显然,我忘了用InterfaceTypeAttribute
装饰C#接口并指定ComInterfaceType.InterfaceIsIUnknown
。至少对于这些COM对象,这是必需的,因为默认的ComInterfaceType.InterfaceIsDual
会导致抛出COMException
s。
例如,接口定义现在在C#中看起来像这样(加上我将一些ref
修复为out
参数,但这不是导致此问题的原因):
[Guid("9C6B4CB0-23F8-49CC-A3ED-45A55000A6D2")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)] // <-- need this
public interface IDxDiagProvider
{
void Initialize(ref DXDIAG_INIT_PARAMS pParams);
void GetRootContainer(out IDxDiagContainer ppInstance);
}
[Guid("7D0F462F-4064-4862-BC7F-933E5058C10F")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)] // <-- need this
public interface IDxDiagContainer
{
void EnumChildContainerNames(uint dwIndex, string pwszContainer, uint cchContainer);
void EnumPropNames(uint dwIndex, string pwszPropName, uint cchPropName);
void GetChildContainer(string pwszContainer, out IDxDiagContainer ppInstance);
void GetNumberOfChildContainers(out uint pdwCount);
void GetNumberOfProps(out uint pdwCount);
void GetProp(string pwszPropName, out IntPtr pvarProp);
}